The invention relates to a smart card connector as well as to switch contact elements, in particular for a smart card connector.
Smart card connectors often use a card presence switch, which comprises switch contact elements. Said switch indicates the presence of a card in the smart card connector, or indicates the end position of the card.
Known switch contacts forming such a card presence switch, have differently shaped contact arms to provide for a predefined contact point. The contact point is defined by two longitudinal crests positioned perpendicular to each other (crossed longitudinal crests). The differently shaped contact arms result in more complex and more expensive cutting tools for the production of the switch contacts. Furthermore, the different geometrical circumstances have to be taken into account during electroplating. Also different processes and courses are necessary during the mounting of said known contact arms being shaped differently from another.
The present invention intends to provide a smart card connector and in particular a switch, and in particular switch contact elements, that can be used in a switch in a smart card connector and which minimize or avoid expenditures during electroplating, cutting and mounting, as well as maintain at the same time a well-defined contact (crossed longitudinal crests).
In short, the invention provides a smart card connector according to claim 1 and 13 as well as a card presence switch and a switch contact element. Preferred embodiments of the present invention are defined in the dependent claims.
The switch in accordance with the present invention has, in general, two identically built and symmetrically arranged switch contact elements, which in particular comprise two identically built and symmetrical arranged contact arms. Therefore only one type of geometry has to be produced during the cutting process. The electro plating can be optimized with respect to one component and still a xe2x80x9ccompletexe2x80x9d switch can be formed using at least two identical specimens of said component. Last but not least, two equal or identical processes can be employed for mounting both of the switch contact elements.
In order to maintain a well defined contact with the arrangement of xe2x80x9ccrossed longitudinal crestsxe2x80x9d a bead in an angle of about 45 degrees is stamped or imprinted in the contact area and, as such, forms a longitudinal crest on the opposite side of the contact area. Since both switch contact elements are being mounted in a mirror inverted (symmetrical) fashion into a contact support, an angle of about 90 degrees is defined at which the two longitudinal crests contact each other and as such a well-defined contact point is formed.
As will be explained further down below, the switch contact elements of the present invention are embodied to be latched into a contact support. Similar to reading contacts, which are normally present in the contact support, the switch contact elements are suitable for Reflow-soldering.
Preferentially, the switch contact elements are provided as normally-closed (NC) contact elements, which allow for a direct sampling of the presence of a card. Since a NC-switch must be provided with a pretension in the contact elements, there is a certain difficulty to guarantee the operation of the switches after the Reflow-soldering. This problem is also addressed by the contact elements of the present invention. The latching plane or the mounting plane of the switching elements of the present invention is perpendicular to the plane, in which the contact arms extend in their width. Now, in order to guarantee the suitability for soldering in a Reflow-oven for such a switch, it is necessary to keep the service pressure generated by the pretension so low that a relaxation of the form material of the contact support, and as such the loss of the pretension of the switch contact elements, is being prevented.
This is being achieved by a specific design measure: The latching plane of the switch contact elements has been intentionally lengthened in accordance with the present invention. Thereby the side area, which transmits the abutment forces on the material of the contact support, is large enough. As a consequence, the surface pressure caused by pretension and/or switch operation is of a magnitude, which causes only very small relaxation losses. The intentional lengthening of the latch plane is being held in a xe2x80x9cpocketxe2x80x9d in the material of the contact support. It thus offers the switch contact element as a whole additional support in the contact support.